Automatic switches



Oct. 18, 1955 2,721,241

W. LEYHAUSEN AUTOMATIC SWITCHES Filed May 16, 1952 2 Sheets-Sheet l lA/VENTOP 17,62 Lao e12,

Oct 1955 w. LEYHAUSEN AUTOMATIC SWITCHES 2 Sheets-Sheet 2 Filed May 16, 1952 wrewrap 3.12/62, an" era,

Ail/e United States Patent 2,721,241 Patented Oct. 18, 1955 lice AUTOMATIC SWITCHES Wilhelm Leyhausen, Numberg, Germany Application May 16, 1952, Serial No. 288,102 Claims priority, application Germany September 28, 1951 laims. (Cl. 200-87) This invention relates to automatic switches as described in the specification of my copending U. S. patent application, filed June 29, 1951, Serial No. 234,211, now Pat. No. 2,671,835 said switches including a base, means defining a contact chamber thereabove, at least one fixed contact in said chamber, (a movable contact normally biased to open position and cooperable therewith, mechanical switching mechanism operably connected with said movable contact for moving the same to and holding the same in circuit closing position, automatic overload release means including an electro-magnetic coil for open ing the circuit in case of a sudden heavy overload, as well as a thermostatic member for opening the circuit in case of a prolonged lesser overload, said elecrto-magnetic coil and thermostatic member cooperable with said switching mechanism to permit reverse movement of said movable contact to circuit breaking position, and superposed housings respectively receiving and separating the said switching mechanism from the switch elements comprising the contacts, the electro-magnetic coil and the thermostatic member which are subjected to electrical stress.

The main object of the present invention is to provide a switch of the kind above described with a contact chamber which is so constructed that the electric are formed by the separation of the contacts is extinguished as soon as possible.

Another object of the invention is to promote the extinguishing of the are by reducing the stray losses of the magnet coil as far as possible.

A further object of the invention is to reduce the volumetric dimensions of the switch.

The accompanying drawings illustrate difierent examples of constructions of the switch according to the invention.

Figure 1 is a longitudinal section through one embodiment of the switch.

Figure 2 is a cross-section of the switch shown in Figure 1.

Figure 3 is a cross-section, partly in end elevation, of another embodiment.

Figure 4 is a longitudinal section through a further embodiment, and

Figure 5 is a crosssection of the embodiment shown in Figure 4.

Referring to Figures 1 and 2, the switch shown includes a base 11 provided with electric connecting strips 12 and 13 and two fixed contacts 21, one of which is connected to the strip 12, the other strip 13 being connected to a bimetallic member 20. The contacts 21 cooperate with a movable contact 22 which is actuated in the known manner by mechanical switching mech anism, which is not shown. On the base 11 is also mounted a magnetic coil 19 provided with an iron core 26 and co-operating with an armature 32. The switch parts are enclosed by a casing mounted on the base 11 and comprising a lower part having a bottom wall 14 and two side walls 15, 16 and a cap 17 acting as a cover. The construction may be such that the two side walls 15 and 16 form constituent parts of the cap which extend down to the bottom wall 14. The lower part of the said casing surrounds the magnetic coil 19 and the bimetallic member 20, the two fixed contacts 21 and the movable contact 22 being housed in a contact chamber 18 within the casing and isolated from the magnetic coil 19 and the bimetallic member 20 by insulating plates 23 and 24 inserted in grooves in the base 11, and at the top from the other parts of the switch by an insulating member 25.

The magnetic coil 19, when energised by a predetermined current, acts on the armature 32 to release the mechanical switching mechanism to move the contact 22 away from the fixed contacts 21 after being engaged therewith, the magnetic coil and armature acting as an overload release in the event of a sudden heavy overload as described in the specification of my copending application Serial No. 234,211, above referred to. The magnetic coil 19 at the same time produces a field which penetrates the contact chamber and extinguishes the electric are produced by the separation of the contacts, at right angles to the direction of movement of the contacts.

The width of the contact chamber 18 is of primary importance for the extinguishing of the said arc, that is to say the dimension of the interior of the contact chamber parallel to the axis of the magnetic coil. While the area of the respective wall surfaces of the contact chamber parallel to the face of the coil should be at least as large as the cross-section of the coil at right angles to its axis, the width of the contact chamber 18, wherever possible, should be less than 6 mm. By this means the core of the ionized column of air due to the arcing when the moving contact is separated from the fixed contacts is quickly cooled. The ratio of the internal width of the contact chamber to the total effective axial length of the coil winding is equal to or greater than 0.8, a coil 19 being employed the ratio of the diameter of which to its axial length being greater than 3. By the combination of the features above-described, especially favourable magnetic and thermal conditions are created which impart to the switch the optimum load-carrying capacity with the minimum dimensions.

in order to reduce the stray losses in the magnetic circuit as far as possible, the magnetic coil 19 is provided with a pole sheet 27 and a counterpole sheet 23, both of which lie directly against the side walls 15, 16 of the casing. The pole sheets 27, 28 are held together by means of screws 29 or rivets passing through the bottom plate 14, and are provided at their upper ends with offset pole shoes 30, 31 for co-operation with the armature 32.

In adidtion thereto, the pole shoes serve to fix the plates 33 and 34 of the switching device, which may be efiected by jointing 35, or by fixing angles 36 and screw connection 37. The switching device is indicated only by the locking lever 38, through which a releasing device is actuated. The plates 33 and 34 of the switching device are united at their upper end to a U-shaped frame through a yoke 39. A suitable slot provided in the yoke acts as a guide for a switching slide 41 provided with an actuating knob 49. The locking lever 38 is acted upon in addition to the armature 32, by the bimetallic member 20 lying near the coil 19, and by the releasing button 42.

The switch may also be so constructed that the two pole shoes 34 and 31 are connected by the insulating member 25, which may also consist of a non-magnetic metal, whilst the two plates 33 and 34 of the switching device then leave the space open towards the top. The counter-pole sheet 28 may also be pressed into the side wall 16.

Figure 3 shows a construction in which the counterpole sheet 28 passes through a recess 28a in the outer wall of the casing, where it forms the outer cover of the switch. The magnet pole sheet 27 may be likewise arranged. In this way, it is possible further to reduce the width of the switch to the extent of the thickness of the pole'sheets.

The example of construction illustrated in Figures 4 and shows how it is possible to reduce the constructional height and simplify the construction.

The contact chamber 52 with the fixed contacts 53 is mounted vertically on the base 51. The magnetic coil 54 is mounted next to the contact chamber, the coil being covered at the top by a widening 52b of the upper cover plate 52a of the contact chamber. The widening 52 may, however, be dispensed with, The effect of the field of the blower coil 54, and therewith the switching power is increased by this that the stray field of the coil is greatly reduced by the two pole plates 55 and 56 which surround the contact chamber and the magnetic coil on the outside. The switching device lies again above the contact chamber and the coil. whole of the switch is obtained by this that the two pole plates 55 and 56 are continued directly into the chamber of the switching device and serve as hearing plates 57 and 58 for the switching device. The two plates 57 and 58 are connected together at the top end by a yoke 59, thereby forming together with the plates 55 and 56 a single U-shaped frame. The two plates may, of course, be connected together by distance bolts. The switching slide 60, which is constructed as a U-shaped bow and is connected with the switch button 61, slides in guiding slots provided in the yoke 59 and is thereby inserted in the switching on position. By pressing down the switching slide 60, the linkage 62, 63, 64- is stretched out, whereby the angularly shaped contact lever 65 is turned around the axis 66, so that the articulated contact rod 67, bridges over the fixed contacts 53 with the resilient contact bridge 68. The link 64 is provided with a locking projection 69 which abuts against a stop lever 70. An arm 71 lies against a side of this lever, against which strikes the cranked arm 72 of the armature 73 when the same is actuated, whereby the lever is lifted and is disengaged from the locking projection. The cranked armature 73 is mounted in outwardly projecting lugs 74 of the pole plate 56. The magnetic coil 54 acting on the armature is mounted eccentrically to the centre line perpendicular to the base with respect to the longitudinal direction of the switch. The fixed contacts 53 and the contact bridge 68 lie in the same eccentric position in the interior of the contact chamber. The space thereby gained next to the magnetic coil is used for the accommodation of the bimetallic member 75.

When the same is bent under the action of heat due to the current, it presses against the arm 76 of the stop lever 70, and causes the same to become disengaged from the locking projection 69. The bimetallic member is secured directly to one electric connecting strip 77, while the other connecting strip 78 leads to one of the fixed contacts 53. The electric connecting strips 77, 78 lie in recesses provided in the base 51 and are secured to the base by means of screws 79. The electric connecting strips are covered on top by means of insulating members 8t), 81 fitted in the recesses. The said insulating members are held in their position by the pole frame 55, 56 or by the contact chamber 52.

I claim:

1. An automatic switch including a base, means defining a contact chamber thereabove, at least one fixed contact in said chamber, a movable contact normally biased to open position and co-operable therewith, mechanical switching mechanism operably connected with said movable contact for moving the same to and holding the same in circuit closing position, automatic overload release means including an electro-magnetic coil cooperable with said switching mechanism to permit reverse movement of said movable contact to circuit breaking position for opening the circuit in case of a sudden heavy An especially simple construction of the overload, and arranged adjacent said contact chamber with its axis perpendicular to the direction of movement of the movable contact so that the magnetic field produced by the coil exerts a blowing action on the electric are produced by the separation of the contacts said electro-magnetic coil having a diameter at least three times that of its axial length, a magnetic pole plate located on the side of said electro-rnagnetic coil remote from the contact chamber and a magnetic counter pole plate on the side of said fixed and movable contacts remote from the coil so as to reduce the stray losses in the magnetic circuit;

2. In an automatic switch including a base, means defining a contact chamber thereabove, at least one fixed contact in said chamber, a movable contact normally biased to open position and co-operable therewith, mechanical switching mechanism operably connected with said movable contact for moving the same to and holding the same in circuit closing position, automatic overload release means including an electro-magnetic coil co-operable with said switching mechanism to permit reverse movement of said movable contact to circuit breaking position for opening the circuit in case of a sudden heavy overload, and arranged adjacent said contact chamber with its axis perpendicular to the direction of movement of the movable contact so that the magnetic field produced by the coil exerts a blowing action on the electric are produced by the separation of the contacts, the combination of a magnetic pole plate located on the side of said electro-magnetic coil remote from the contact chamber and a magnetic counter pole plate located on the side of said fixed and movable contacts remote from the coil, so as to reduce the stray losses in the magnetic circuit, with pole shoes on said pole plates at the upper ends thereof and an armature located above said pole shoes and co-operable therewith for releasing the automatic switching mechanism to permit said reverse movement of the movable contact.

3. In an automatic switch including a base, means defining a contact chamber thereabove, at least one fixed contact in said chamber, a movable contact normally biased to open position and co-operable therewith, mechanical switching mechanism operably connected with said movable contact for moving the same to and holding the same in circuit closing position, automatic overload release means including an electro-magnetic coil cooperable with said switching mechanism to permit reverse movement of said movable contact to circuit breaking position for opening the circuit in case of a sudden heavy overload, and arranged adjacent said contact chamber with its axis perpendicular to the direction of movement of the movable contact so that the magnetic field produced by the coil exerts a blowing action on the electric are produced by the separation of the contacts, the combination of a magnetic pole plate located on the side of said electro-magnetic coil remote from the contact chamber and a magnetic counter pole plate located on the side of said fixed and movable contacts remote from the coil, said pole plate and counter-pole plate having a surface area substantially equal to that of the coil crosssection, so as to reduce the stray losses in the magnetic circuit, with pole shoes on said pole plates at the upper ends thereof and an armature located above said pole shoes and co-operable therewith for releasing the automatic switching mchanism to permit said reverse movement of the movable contact.

4. An automatic switch including a base, means defining a contact chamber thereabove, at least one fixed contact in said chamber, a movable contact normally biased to open position and co-operable therewith, mechanical switching mechanism operably connected with said movable contact for moving the same to and holding the same in circuit closing position, automatic overload release means including an electro-magnetic coil cooperable with said switching mechanism to permit reverse movement of said movable contact to circuit breaking position for opening the circuit in case of a sudden heavy overload, and arranged adjacent said contact chamber with its axis perpendicular to the direction of movement of the movable contact so that the magnetic field produced by the coil exerts a blowing action on the electric are produced by the separation of the contacts said electro-magnetic coil having a diameter at least three times that of its axial length, a magnetic pole plate located on the side of said electro-rnagnetic coil remote from the contact chamber and a magnetic counter-pole plate on the side of said fixed and movable contacts remote from the coil so as to reduce the stray losses in the magnetic circuit, said pole plate and counter-pole plate extending upwardly to above the said switching mechanism and joined together at the top to form a cover for the switching mechanism.

5. An automatic switch including a base, means defining a contact chamber thereabove, at least one fixed contact in said chamber, a movable contact normally biased to open position and co-operable therewith, mechanical switching mechanism operably connected with said movable contact for moving the same to and holding the same in circuit closing position, automatic overload release means including an electro-magnetic coil cooperable with said switching mechanism to permit reverse movement of said movable contact to circuit breaking position for opening the circuit in case of a sudden heavy overload, and arranged adjacent said contact chamber with its axis perpendicular to the direction of movement of the movable contact so that the magnetic field produced by the coil exerts a blowing action on the electric arc produced by the separation of the contacts said electro-magnetic coil having a diameter at least three times that of its axial length, a magnetic pole plate located on the side of said electro-magnetic coil remote from the contact chamber and a magnetic counter pole plate on the side of said fixed and movable contacts remote from the coil so as to reduce the stray losses in the magnetic circuit, said pole plate and counter-pole plate extending upwardly to above the switching mechanism to serve as bearing supports for the switching mechanism and the upper wall of the contact chamber having a prolongation extending above the electro-magnetic coil so as to cover it.

References Cited in the file of this patent UNITED STATES PATENTS 2,456,945 Iglehart Dec. 21, 1948 2,494,868 Geremia Jan. 17, 1950 2,573,306 Casey Oct. 30. 1951 

